Retroreflective Articles with Cube Corners and Adhesive Barrier
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Solution Overview
Problem
Retroreflective sheeting technologies face challenges with sealing films that reduce active area, increase manufacturing costs, and create undesirable patterns, while metalized cube corners lack sufficient durability and whiteness for daytime viewing.
Innovation Solution
The development of retroreflective articles without sealing films or metalized cube corners, utilizing a structured surface with cube corner elements and a pressure sensitive adhesive, where a low refractive index layer and barrier layer prevent adhesive flow and maintain retroreflectivity, creating optically active and inactive areas.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If sealing films are used to protect the air interface of cube corner elements, then retroreflective light intensity is maintained, but the total active area is reduced and manufacturing cost increases
Solution Approach 1:
The patent removes the sealing film from the retroreflective sheeting structure, extracting the protective function and replacing it with an adhesive layer that bonds the sheeting to the substrate. This eliminates the sealing film's obstruction of the active area while maintaining protection through alternative means.
Solution Approach 2:
The patent combines the adhesive function and the protective function into a single adhesive layer. This layer both bonds the retroreflective sheeting to the substrate and protects the cube corner elements, eliminating the need for a separate sealing film and thereby preserving active area.
2Reliability
If sealing films are used to protect the air interface of cube corner elements, then retroreflective light intensity is maintained, but manufacturing cost increases
Solution Approach 1:
The patent combines the adhesive function and the protective function into a single adhesive layer. This layer both bonds the retroreflective sheeting to the substrate and protects the cube corner elements, eliminating the need for a separate sealing film and thereby reducing manufacturing cost.
Solution Approach 2:
The patent removes the sealing film from the structure, extracting its protective function and replacing it with the adhesive layer. This simplifies the manufacturing process and reduces material costs while maintaining the necessary protection.
3Reliability
If metalized cube corners are used for retroreflection, then durability is improved, but whiteness and daytime viewing quality are insufficient
Solution Approach 1:
The patent employs a composite structure combining cube corner elements made from materials with high refractive index (for durability and retroreflective performance) with a white pigmented adhesive layer (for daytime whiteness). This composite approach achieves both durability and adequate whiteness for daytime viewing.
Solution Approach 2:
The patent applies different properties to different parts of the system: the cube corner elements provide durability and retroreflective function, while the white pigmented adhesive layer provides daytime visibility and whiteness. Each component is optimized for its specific function.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This solution enhances retroreflectivity, reduces manufacturing costs, and provides a uniform appearance without the need for sealing films, while ensuring durability and adequate whiteness for daytime visibility.
Implementation Method 1
The one or more optically active areas include a low refractive index layer or material adjacent to a portion of the structured surface
Implementation Method 2
The one or more optically inactive areas include a pressure sensitive adhesive adjacent to a portion of the structured surface. The pressure sensitive adhesive substantially destroys the retroreflectivity of the portions of the structured surface that are directly adjacent thereto.
Implementation Method 3
The barrier layer has sufficient structural integrity to substantially prevent flow of the pressure sensitive adhesive into the low refractive index layer
Implementation Method 4
Generally, light that is incident on a corner cube element from a light source is totally internally reflected from each of the three perpendicular cube corner optical faces and is redirected back toward the light source
Data Source
AI summary
This disclosure generally relates to retroreflective articles and methods of making such articles.